The unnecessary roughness penalty was the second of the game for Johnson, who was earlier flagged for a late hit on Peyton Manning after the quarterback was sacked by Mario Williams. The NFL confirmed the fine on Friday.
Johnson told Houston television station KRIV he wasn't trying to hurt Fletcher.
"I was in the air when the whistle blew," Johnson said. "You win some, and you lose some."
The Texans finish their season Sunday against Jacksonville.
Copyright 2007 by The Associated Press
